Mr Goldsmith is seen with his daughter Tallulah at Pippa Middleton's wedding this year

Gary Goldsmith, the brother of Kate Middleton's mother Carole, admitted knocking his fourth wife unconscious with a "left hook". The taxi driver reportedly challenged Gary, 52, after witnessing the attack, but he became very aggressive.

"They both got out of the taxi and he [Mr Shepherd] describes Mrs Goldsmith slapping her husband to the face".

Kate Middleton's uncle Gary Goldsmith appeared in court Tuesday, and admitted to physically assaulting his wife following a drunken night out, according to the BBC.

The newspaper reported that prosecutor Kate Shilton said of the October incident, "Mr. Goldsmith began to shout at her and both parties were drunk, having been drinking throughout the evening".

'He then describes how Mr Goldsmith punches her hard in the face using a left hook. "Mrs Goldsmith has then fallen backwards". "She appears to be unconscious, she isn't moving".

The couple had been at a charity auction at Home House in Portman Square, Marylebone before they clashed.

Goldsmith pleaded guilty to one count of assault by beating.

Westminster Magistrates' Court heard that Goldsmith - who is the younger brother of Kate's mother Carole Middleton - left Julie-Ann Goldsmith unconscious outside of their London home.

The maximum penalty for his crime is of six months imprisonment, yet he will likely just face community service. Shepherd said the couple had got in a row before Julie-Anne slapped her husband across the face.